[Yt-svn] yt-commit r1640 - trunk/yt

[dcollins at wrangler.dreamhost.com]

Author: dcollins
Date: Thu Feb 25 12:34:14 2010
New Revision: 1640
URL: http://yt.enzotools.org/changeset/1640

Log:
Adding physical constants module.  Currently only clones things already used in yt.

Added:
   trunk/yt/physical_constants.py

Added: trunk/yt/physical_constants.py
==============================================================================
--- (empty file)
+++ trunk/yt/physical_constants.py	Thu Feb 25 12:34:14 2010
@@ -0,0 +1,42 @@
+#
+# Physical Constants and Units Conversion Factors
+#
+
+# Masses
+mass_hydrogen_cgs = 1.67e-24 # g
+mass_electron_cgs = 9.11e-28 # g
+print "poop"
+# Velocities
+speed_of_light_cgs = 2.99792458e10 # cm/s, exact
+
+# Cross Sections
+cross_section_thompson_cgs = 6.65e-25 # cm^2
+
+# Physical Constants
+boltzmann_constant_cgs = 1.3806504e-16 # erg K^-1
+gravitational_constant_cgs  = 6.67428e-8 # cm^3 g^-1 s^-2
+
+rho_crit_now = 1.8788e-29 # g times h^2 (critical mass for closure, Cosmology)
+
+# Misc. Approximations
+mass_mean_atomic_cosmology = 1.22
+mass_mean_atomic_galactic = 2.3
+
+# Conversion Factors
+# length
+mpc_in_mpc = 1
+mpc_in_kpc = 1e3
+mpc_in_pc  = 1e6
+mpc_in_au  = 2.063e11
+mpc_in_rsun =4.43664e13
+mpc_in_miles =1.917e19
+mpc_in_cm  = 3.0857e24
+
+
+#Short cuts
+G = gravitational_constant_cgs
+me = mass_electron_cgs
+mp = mass_hydrogen_cgs
+clight = speed_of_light_cgs
+kboltz = boltzmann_constant_cgs
+sigma_thompson = cross_section_thompson_cgs